Core consumer prices outside of food and energy posted the biggest increase in April in more than a year, suggesting that an improving U.S. economy is finally starting to lift prices. That could prompt the Federal Reserve to start raising interest rates later this year.

Overall consumer prices edged up 0.1 percent for the third straight climb, the Labor Department said Friday. Overall gains were held back by a 1.3 percent drop in energy costs.

But excluding food and energy, core inflation rose 0.3 percent in April, marking the biggest one-month increase since January 2013. That means core inflation has risen at an annual rate of 2.6 percent over the past three months — the fastest pace in four years.

Paul Ashcroft, chief U.S. economist at Capital Economics, said while overall inflation still remains very low, the trend in core prices is likely to spark concerns at the central bank. The Fed has kept interest rates at ultra-low levels for the past six years to help the economy recover from a deep recession.

-- Associated Press